Rubber article reinforced with nylon filaments



Nov. 16, 1965 v v, sKEEN ETAL 3,218,222

RUBBER ARTICLE REINFORCED WITH NYLON FILAMENTS Original Filed June 9,1960 NYLON YARN IMPREGNATED WITH RTAlN IGLYCERIDES D NFOR G A RUBBER ACLE.

INVENTOR GINIA V. SKE LVIN J. WAITKUS United States Patent Office3,218,222 Patented Nov. 16, 1965 3,213,222 RUBBER ARTICLE REINFORCEDWITH NYLON FILAMENTS Virginia V. Skeen, Decatur, Ala., and Calvin J.Waitlrus, Mountain Lakes, N.J., assignors, by mesne assignments, toMonsanto Company, a corporation of Delaware- Original application June9, 1960, Ser. No. 34,863, now Patent No. 3,160,511, dated Dec. 8, 1964.Divided and this application Feb. 7, 1962, Ser. No. 171,738

5 Claims. (Cl. 16192) This invention relates to a rubber articlereinforced with nylon filaments.

Nylon filaments have made a substantial penetration into the tire cordmarket and other markets of similar rubber-fabric composite articles. Inthe main, the entry of nylon filaments in these fields of applicationshas been at the expense of cellulosic filaments and resulted because ofthe many superior physical properties of nylon filaments. At presentvirtually all airplane and large offthe-road equipment tires arereinforced with nylon cord. Furthermore, a substantial portion ofreplacement pas senger tires today contain nylon cord. Noteworthy is thefact that virtually all of the premium passenger car tires arereinforced with nylon cord.

One of the former drawbacks to the use of nylon cordcontaining tires wasthe tendency of such tires to increase undesirably in size during normaluse conditions. However, during the past few years hot-stretch processesand apparatus have been developed and used to reduce the growth tendencyof nylon cord tires significantly. These means have eliminated to agreat degree the problem of tire dimensional growth. Another drawback ofnylon cord-containing tires at a time past was the somewhat lowrubber-to-cord adhesion. This latter problem has been solved by the useof certain bonding agents applied to the nylon cord prior to the timethe nylon cord is incorporated in the rubber. Unfortunately, thehot-stretch procedures have given rise to certain concomitant problems.One of these problems is that the finishing compositions normallyapplied to nylon filaments to improve their pliability and to impart thedesired lubricity thereto tend to deteriorate during the hot-stretchingoperation. This tendency is quite objectionable in that it causesadverse effects in the filaments and results in decomposition of thefinishing compositions and attendant liberation of obnoxious smoke andfumes. In other words, the heretofore known finishing compositions fornylon filaments do not perform satisfactorily during hot-stretching ofsuch filaments.

Most, if not all, of the nylon filaments today are manufactured by themelt spinning process. In such process the nylon polymer is heated tothe molten or plastic state but below the decomposition temperaturethereof. The molten or plastic mass is extruded at a constant rate andunder pressure through small orifices in the face of a spinneret to formmolten streams of polymer. The molten polymer streams are cooled andsolidified into individual filaments. The filaments are then broughttogether, and a finish composition is applied to the filaments. At thisstage in their production the nylon filaments are not highly orientedand have relatively low tensile strength. To orient the nylon filamentsand thereby to increase greatly the strength thereof, they are stretchedin one or more stages to a desired extent by attenuating them by meansof thread advancing devices such as two godets operated at apredetermined speed diiferential therebetween. It is quite advantageousto localize the point of drawing by the employment of a yarn brakingdevice, for example, a snubbing pin, located between the godets. In onehot-stretching procedure, the nylon filaments while traveling betweenthe snubbing pin and second godet are heated, such as by passing themacross the surface of a heater plate maintained at a suitable elevatedtemperature. At this point the deterioration of the known finishingcompositions is manifest by the visible, offensive smoking and fuming ofthe compositions, giving rise to very serious processing problems. Afterbeing hot-stretched the filaments are collected, twisted; and aplurality of ends are plied into cord. Before being incorporated inrubber, the nylon cord usually is passed through a hot-dip bathcontaining a dispersion of latex and a bonding agent such as a mixtureof a dihydric benzene and formaldehyde. The thus impregnated cord isstretched a relatively small extent and dried under tension. Prior artfinishing compositions for nylon filaments tend to induce foaming of thehot-dip bath.

An object of the invention is to provide articles of manufactureembodying nylon filaments impregnated with said composition, whether inthe form of cords, fabric, and rubber articles reinforced with suchnylon filaments.

Other objects will appear more fully hereinafter.

The drawing is a perspective view illustrating a nylon yarn impregnatedwith triglycerides and reinforcing a rubber article.

According to this invention there is prepared a new and usefulcomposition comprising an aqueous emulsion of a particular class offatty acid esters defined below or a mixture of such esters in thepresence of a suitable emulsifying agent. Nylon filaments areimpregnated therewith and the impregnated filaments are dried.Advantageously the impregnation is carried out during the manufacture ofthe filaments and prior to the stage in their manufacture at which theyare stretched to impart increased molecular orientation therein. Theimpregnated filaments are rendered more tractable in textile handlingoperations and particularly can be effectually hot stretched at elevatedtemperatures of above C. but below the sticking point of the filaments.When incorporated in rubber articles for reinforcing the same, thearticles exhibit high flexural strength and accordingly have a longerservice life. The improvement is especially noteworthy where the articleis repeatedly flexed under elevated temperature conditions, as apneumatic tire would be during use.

The class of fatty acid esters employed in the practice of the instantinvention are mixed triglycerides and can be represented generally bythe following formula RCOOCHz RCOOOH RCOOCHQ wherein R designatessaturated or unsaturated aliphatic radicals. Two of the aliphaticradicals contain 1 to 5 carbon atoms and at most one ethyleneunsaturation. The other aliphatic radical contains 12 to 22 carbon atomsand from 0 to 5 double carbon to carbon bonds. The lower acyl groups maybe located in 'y, p, or oz, '7 positions with respect to the glycerylradical, the location of the respective acyl groups not being criticalto the present invention.

Among these defined esters or mixed triglycerides are diaceto-laurin,diaceto-myristin, diaceto-palmitin, diacetostearin, diaceto-arachidin,diaceto-behenin, diaceto-lignocerin, diaceto-laurolein,diaceto-myristolein, diaceto-palmitolein, diaceto-olein,diaceto-gadolein, diaceto-erucin, diaceto-ricinolein, diaceto-linolein,diaceto-linolenin, diaceto-elaeostearin, diaceto-licanin,diaceto-arachidonin, and diaceto-clupanodonin. Of the just mentionedtriglycerides the preferred compounds are diaceto-ricinolein,diaceto-linolein, and diaceto-linolenin, as well as mixtures of thesethree compounds. As indicated above the lower fatty acid substituentscan be either in the alpha, beta, or the alpha, gamma positions.

Other suitable triglycerides include dipropiono-laurin,dipropiono-myristin, dipropiono-palmitin, dipropionostearin,dipropiono-arachidin, dipropiono-behenin, dipropin0-lignoceriu,dipropiono-laurolein, dipropionomyristolein, dipropiono-palmitolein,dipropiono-olein, dipropiono-gladolein, dipropiono-erncin,dipropiono-ricinolein, dipropiono-linolein, dipropiono-linolenin,dipropionoelaeostearin, dipropiono-licanin, dipropiono-arachidonin, anddipropiono-clupanodonin; dibutyro-laurin, dibutyromyristin,dibutyro-palmitin, dibutyro-stearin, dibutyroarachidin,dibutyro-behenin, dibutyro-lignocerin, dibutyrolaurolein,dibutyro-myristolein, dibutyro-palmitolein, dibutyro-olein,dibutyro-gadolein, dibuty'ro erucin, dibutyroricinolein,dibutyro-elaeostearin, dibutyro-licanin, dibut'yro-ara'chidonin, anddibutyro-clupanodonin; divalerolaurin, di'v'aleroqnyristin,divalero-palmitin, divalerO- s'tearin, divalero-arachidin,divalero-behenin, divalerolignocerin, divalero-laurolein,divalero-myri-stolein, di- Valero-palmitolein, divalero-olein,divalero-gadolein, divalero-erucin, divalero-ricinolein,divalero-linolein, divalero-linolenin, divalero-elaeostearin,divalero-licanin, divalero-arachidonin, and divalero-clupanodonin;dicaprolaurin, dicapro-myristin, dicapro-palmitin, dicapro-stearin,dicapro-archidin, dicapro-behenin, dicapro-lignocerin,dicapro-laurolein, dicapro-myristolein, dicapro-palmitolein,dicapro-olein, dicapro-gadolein, dicapro-erucin, dicaproricinolein,dicapro-linolein, dicapro-linolenin, dicaproelaeostearin,dicapro-licanin, dicapro-arachidonin, and dicapro-clupanodonin;dicrotono-laurin, dicrotono-myristin, dicrotono-palmitin,dicrotono-stearin, dicrotono-arachidin, dicrotono-hehenin,dicrotono-lignocerin, dicrotono-laurolein, dicrotono-myristolein,dicrotono-palmitolein, dicrotono-olein, dicrotono-gadolein,dicrotono-erucin, dicrotono-ricinolein, dicrotono-linolein,dicrotono-linolenin, dicrotono-elaeostearin, dicrotono-licanin,dicrotono-archidonin, and dicrotono-clupanodonin and otherscorresponding to the above structural formula. In general, methods forproducing these mixed triglycerides are known and involve conventionaltriesterification of glycerol with the selected fatty acids.

The finishing composition of the present invention is an aqueousemulsion, and hence a suitable emulsifying agent normally is employed asan ingredient thereof for rendering the emulsion more stable. While anumber of emulsifying agents can be employed and are within the scope ofthe general disclosure, the non-ionic surface active agents are thepreferred class of materials. Of the non-ionic surface active agents thepolyethers are the preferred emulsifying agents, including alkyla-rylpolyoxyethylene ethanols, alkyl polyoxyethylene ethanols, alkylarylpolyoxypropylene ethanols, alkyl polyoxypropylene ethanols, etc. Ingeneral these polyether compounds are prepared by reacting a suitablemonohydric or polyhydric alcohol with suitable amounts of alkyleneoxide. Ethylene oxide is the most often used alkylene oxide in view ofits attractive price, but propylene oxide may be used in whole or inpart with ethylene oxide.

Suitable primary alcohols reactable with ethylene oxide and the like forpreparing the emulsifying agents employed herein include dodecylalcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, palmitoleylalcohol, oleyl alcohol, linoleyl alcohol, carnaubyl alcohol and others.The long chain aliphatic radical of these alcohols may have from 10-24and higher carbon atoms in the chain and O to 2 double bonded carbons.The preferred alcohols are C C compounds. The primary alcohols of thejust described type are condensed with 5 to 30 moles of ethylene oxideor the alkylene oxide.

As indicated alkylaryl polyoxyalkylene alcohols are also useful asemulsifying agents. These compounds are generally prepared by reacting 8to 30 moles of an alkylene oxide such as ethylene oxide with alkylsubstituted phenols. The alkyl group or groups substituted on thebenzene ring contain 2 to 20 carbon atoms in each chain a d prefe ablyfrom .5 to 7 carbon atoms. Trade names 4 of these alkylarylpolyoxyalkylene alcohols include Igepol CA, Igepol #300, Igepol CO,Antarox A-400, Triton X-lO, Emulphor DDT, and are believed to have theformula:

Suitable polyhydric alcohols condensed with alkylene oxide include, forexample, sorbitan monolaureate polyoxyethylene condensate (20 moles ofethylene oxide), sorbitan monopalmitate polyoxethylene condensate (40moles of ethylene oxide), sorbitan monostearate polyoxyethylenecondensate (60 moles of ethylene oxide), sorbitan monooleatepolyoxyethylene condensate moles of ethylene oxide), and the like. Againthe preferred alkylene oxide is ethylene oxide, however as previouslyindicated, propylene oxide is known to be an equivalent therefor in someinstances.

The ratio of emulsifying agent to the triglyceride ester component canbe varied within rather wide limits, the requirement being that enoughemulsifying agent be employed so that the emulsion is stable. However,it has been found that in order to prepare stable emulsions of theesters above defined and essential to the present composition, thepercentage of emulsifying agent, based on the weight of the ester plusthe emulsifying agent, can be about 10 percent to about 50 percent. Thepreferred percentage is about 30 to about 40 percent by Weight.

In order to obtain the benefits of the treatment of this invention, itis generally necessary that the triglyceride compound remain in or onthe nylon filaments at the time the filaments are hot-stretched and atthe time they are employed in a rubber composite article in an amountfrom about 0.05 to about 3.0 percent based on the weight of thefilaments.

For convenience, the finishing composition of the present invention isapplied to a longitudinally traveling bundle of filaments by employmentof a roller partly immersed in the composition or a wick material partlyimmersed in the composition, the traveling filaments coming into contacttherewith. In place of such manner of application, the finishingcomposition can be impregnated in the nylon filaments in any othersuitable manner, such as by immersion in a bath of the composition or byspraying or brushing the composition on the filaments.

The relative concentration of the triglyceride ester component in thefinishing composition can be varied considerably in obtainingimpregnation of the ester on the filaments in the above-mentionedamounts. The concentration will depend, among other things, on theparticular method of impregnation employed, and on the form of filamentstreated. Emulsions ranging from about 0.5 to about 20 percent or higherof the triglyceride ester component based on the Weight of the finishingcomposition are quite suitable for impregnating commercial nylonfilaments.

The new and useful filament finishing composition can be prepared in thefollowing manner. The selected triglyceride ester component andemulsifying agent therefor are intimately agitated together with thedesired quantity of water at temperatures of about 25 C. to 50 C. In oneexcellent way of preparing an emulsion of good stability, theingredients are agitated in a high shear liquid blender or mill, such asa Waring Blendor. Generally, an agitation time of about 5 to 30 minutesat temperatures from 0 to C. is sulficient to prepare emulsionsexhibiting good stability. It is preferred, however, that the newfinishing compositions be prepared by blending the triglyceridecomponent with the emulsifying agent at a temperature of about 40 C. to45 C., subsequently add ing the required amount of water and thereaftervigorously agitating the emulsion for about 20 to 30 minutes at about 15C. to 30 C. Where desirable, the emulsion is cooled by suitable meansduring the agitation period.

Nylon, as is well known, is a high molecular weight linear polymer whichcontains recurring carbonamide groups as an integral part of the mainpolymer chain separated by at least two carbon atoms. Broadly speaking,nylon polymers are of two general types. One type of nylon is obtainablefrom polymerizable monoaminomonocarboxylic acids and their amide-formingderivatives, for example e-caprolactam and a-pyrrolidone, knowngenerically in their polymerized form as nylon-6 and nylon-4,respectively. The other type of commercial nylon is obtainable fromsuitable primary or secondary diamines and suitable dicarboxylic acidsor amideforming derivatives thereof. Among the latter type are polymersformed by the reaction of tetramethylene diamine, pentamethylenediamine, hexamethylene diamine and the like with adipic acid, subericacid, sebacic acid and the like. The polymerization product ofhexamethylene diamine and adipic acid has the generic name of nylon-66.

The manner in which the foregoing aspects of the invention are attainedwill appear more fully from the following example, in which reference ismade to typical and preferred procedures in order to indicate more fullythe nature of the invention, but without intending to limit theinvention thereby. In the example all parts and percentages are byweight unless otherwise indicated.

Example Eighteen parts of diaceto-ricinolein was combined with 2 partsof an emulsifier composed of a mixture of myristyl alcohol, cetylalcohol, stearyl alcohol, arachyl alcohol, palmitoleyl alcohol, oleylalcohol, and linoleyl alcohol having been condensed with 20 moles ofethylene oxide per mole of alcohol. The mixture of triglyceride estercomponent and emulsifying agent was homogenized with 180 parts of waterto form a stable emulsion. The emulsion was applied to a bundle of 140nylon-66 filaments having an ultimate total denier of 840 between thespinneret employed in the melt-spinning of the filaments and the pointof first take-up in an orderly manner on a spin bobbin. The filamentswere hot drawn on a conventional draw-twist machine employing two setsof rolls, a drawing pin in the yarn path between said rolls, a heatedplate in the yarn path between said pin and said second set of rolls,and a ring twister take-up assembly. Between the two sets of rolls, thefilaments are stretched about 5 times. The filaments attained atemperature of about 180 C. during the operation.

The finishing composition showed no signs of decomposition and wascompletely stable at the temperature employed.

When a finish heretofore known and composed in the main of sulfonatedpeanut oil and mineral oil was applied to the filaments in the samemanner as stated above in place of the triglyceride ester, olfensivesmoke and fumes were given off during the processing.

The filaments containing the novel finishing composition and thosecontaining the heretofore known finish were separately processed intotire cord, and the cord incorporated into a pneumatic tire by standardand conventional procedures. The nylon filament cord containing thetriglyceride ingredient processed well in the hotdip bath and exhibitedimproved and more uniform adhesion characteristics with respect to therubber of the tire as compared with cord containing the heretofore knowncomposition. The nylon filament cords were used as the reinforcingtextile fabrics in pneumatic tires by standard procedure. The tires wereof the type used in high speed racing vehicles. Tire failure occurred inthe tires containing the heretofore known finish long before failureoccurred in the tires impregnated with the triglyceride ingredient.

When other triglyceride ester materials of the defined class areemulsified with other non-ionic emulsifying agents, similarly excellentresults are obtained in the production of nylon-66 and nylon-6 tirecord.

Thus nylon filaments treated with the new finishing compositions abovedescribed are especially adapted for use in the rubber-fabric compositearticles since they may be hot-stretched efficiently without theoccurrence of obnoxious smoking and fuming. In addition to rendering thefilament more amenable to hot-stretching, the new finishing compositionshave numerous other advantages such as providing increased adhesionbetween the rubber and filaments and increased resistance of therubber-fabric composite articles to heat deterioration upon repeatedrapid flexing, as in the case of pneumatic tires.

It is to be understood that the foregoing description is given merely byway of illustration and that many variations may be made therein,without departing from the spirit of the invention.

This application is a divisional application of pending applicationSerial No. 34,863, filed June 9, 1960, the latter application being acontinuation-in-part application of application Serial No. 797,014,filed March 4, 1959, which is now abandoned.

What is claimed is:

1. A rubber article reinforced with nylon cord, the filaments of whichare coated with a mixed triglyceride having the structural formula:

RCOOCH;

RCOO H RCOO Hz wherein R designates aliphatic radicals, two of whichhaving 1 to 5 carbon atoms and at most one double carbon to carbon bondand one of which having 12 to 22 carbon atoms and at most 5 doublecarbon to carbon bonds in an amount of about 0.05 to about 3.0 percentby weight of the filaments.

2. The article of claim 1 wherein the nylon filaments are made ofnylon-66 polymer.

3. The article of claim 1 wherein the nylon filaments are made ofnylon-6 polymer.

4. The article of claim 2 wherein the triglyceride is diacetoricinolein.

5. The article of claim 3 wherein the triglyceride is diacetoricinolein.

References Cited by the Examiner UNITED STATES PATENTS Re. 23,451 1/1952 Mighton et al. 161227 2,838,455 6/1958 Tompkins 252- 3,113,36912/1963 Barrett et al. 117139.5

EARL M. BERGERT, Primary Examiner.

1. A RUBBER ARTICLE REINFORCED WITH NYLON CORD, THE FILAMENTS OF WHICHARE COATED WITH A MIXED TRIGLYCERIDE HAVING THE STRUCTURAL FORMULA:R-COO-CH2-CH(-OOC-R)-CH2-OOC-R WHEREIN R DESIGNATES ALIPHATIC RADICALS,TWO OF WHICH HAVING 1 TO 5 CARBON ATOMS AND AT MOST ONE DOUBLE CARBON TOCARBON BOND AND ONE OF WHICH HAVING 12 TO 22 CARBON ATOMS AND AT MOST 5DOUBLE CARBON TO CARBON BONDS IN AN AMOUNT OF ABOUT 0.05 TO ABOUT 3.0PERCENT BY WEIGHT OF THE FILAMENTS.